The Cubs optioned Assad to Triple-A Iowa on Friday, Taylor McGregor of Marquee Sports Network reports.
The move opens up a spot on the Cubs' active roster for Daniel Palencia, who was activated from the 60-day injured list in a corresponding move. Assad was promoted to the Cubs' bullpen on Monday and worked in long-relief against the White Sox on Tuesday, when he allowed two hits while striking out two batters across three scoreless frames. He's started in all five of his outings in Triple-A, where he has a 7.31 ERA and 2.06 WHIP across 16 innings this season.